Open _template.php and save it as phpquotes.php. Paste this inside the PHP tag:
echo "<p class="blue">Hello world</p>";
You can probably see that this should create a paragraph complete with a class attribute.
Upload the page and try it in a browser and it will not work. You should see an error message something like this:
Parse error: syntax error, unexpected 'blue' (T_STRING), expecting ',' or ';' in E:\web\phpquotes.php on line 22
The reason is that echo expects to be given some text inside quotation marks. In the above line it will start with the first set of quotes and then find a second set (just after the first e). Then it sees more text but the text doesn't make sense as it is not a command but it also can't be part of the text as the quotes have been closed.
So when you see parse error it's probably something to do with quotes or punctuation in the code. To fix this one you change it to this:
echo "<p class=\"blue\">Hello world</p>";
This is known as escaping the quotes. The extra backslash tells the server that the following character is to be treated as text not as part of the code. Mostly this is used for quotes but you will see a few other uses later. Now the quoted text only stops at the end (the un-escaped quotes) as you wanted.
You only escape the quotes inside text within the PHP tag block not in the whole Web page (e.g. in the link element at the top of your page.. Only code which is interpreted by the PHP server before sending the results to the browser will cause a problem. This can be very frustrating so make sure you have grasped the concept.